Many different orthopedic casting materials have been developed for use in the immobilization of broken or otherwise injured body limbs. Some of the first casting materials developed for this purpose involved the use of plaster of Paris bandages consisting of a mesh fabric (e.g., cotton gauze) with plaster incorporated into the openings and onto the surface of the mesh fabric. Subsequently, improved casting materials were developed consisting of a knit fabric made from a high modulus fiber (e.g., fiberglass) impregnated with a polyisocyanate prepolymer. The prepolymer typically was the reaction product of a polyisocyanate and a hydrophilic polyol such as a polyether- or polyester-based polyol. One problem with such materials, however, was that their strength decreased significantly once they got wet.